Goals by Mason Mount and Hakim Ziyech earned Chelsea a hard-fought 2-1 victory at Watford to remain top of the Premier League table.
Watford made a bright start before play was stopped due to a medical emergency in the crowd, with the supporter involved stabilised before play resumed.
Mount then shot against a post before the midfielder opened the scoring in the 29th minute, finding the bottom corner after being teed up by Kai Havertz.
Watford responded well and they levelled when Emmanuel Dennis rounded off a swift counter-attack with a low shot on 43 minutes.
Tom Cleverley slipped when through on goal and Watford were left to rue that chance as substitute Ziyech blasted in from Mount's square pass to make it 2-1 after 72 minutes.
Edouard Mendy tipped Juraj Kucka's late free-kick over the crossbar as Chelsea stood firm to return to winning ways and move on to 33 points.
Watford stay 17th on 13 points, three clear of the relegation zone.
See: Watford report | Chelsea report
Next fixtures
Watford: 4 Dec v Man City (H)
Chelsea: 4 Dec v West Ham (A)
Match officials
Referee: David Coote. Assistants: Stuart Burt, Nick Hopton. Fourth official: Michael Salisbury. VAR: Darren England. Assistant VAR: Wade Smith.
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